akira 21SHS3/CE User manual

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Model No: 21SHS3-CE.doc

Version 1.0

Group Model:

21SHS3

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Model No: 21SHS3-CE.doc

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CONTENT

SAFETY NOTICE ................................................................................................................................... 4

GENERAL DESCRIPTION .................................................................................................................... 6

TECHNICAL SPECIFICATION ............................................................................................................. 7

GENERAL SPECIFICATION................................................................................................................. 8

HORIZONTAL AND VERTICAL CIRCUIT ......................................................................................... 9

CHASSIS BLOCK DIAGRAM ............................................................................................................. 10

FAULT FINDING TREES..................................................................................................................... 11

IC BLOCK DIAGRAM ......................................................................................................................... 18

FACTORY MENU

................................................................................................................................ 40

EXPLODED VIEW AND PART NAME .............................................................................................. 43

BOM LIST ............................................................................................................................................. 44

CIRCUIT DIAGRAM............................................................................................................................ 61

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Model No: 21SHS3-CE.doc

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SAFETY NOTICE

WARNING: BEFORE EXAMINING AND

SERVICING THIS CHASSIS, READ

CAREFULLY THE FOLLOWING

SAFETY INSTRUCTIONS.

X-RAY RADIATION PRECAUTION

1. The primary source of X-RADIATION in television receiver is the picture tube. The picture tube

is specially constructed to limit X-RADIATION emissions. For continued X-RADIATION

protection, the replacement tube must be the same type as the original including suffix letter.

Excessive high voltage may produce potentially hazardous X-RADIATION. To avoid such

hazards, the high voltage must be maintained within specified limit. Refer to this service manual,

high voltage adjustment for specific high voltage limit. If high voltage exceeds specified limits,

take necessary corrective action. Carefully follow the instructions for +B1 volt power supply

adjustment, and high voltage check to maintain the high voltage within the specified limits.

2. The EHT must be checked every time the receiver is serviced to ensure that the CRT does not emit

X-ray radiation as result of excessive EHT voltage. The nominal EHT for this receiver is 22KV at

zero beam current (minimum brightness) operating at AC 220V. The maximum EHT voltage

permissible in any operating circumstances must not exceed 25KV. When checking the EHT, use

the High Voltage Check procedure in this manual using an accurate EHT voltmeter.

3. The only source of X-RAY radiation in this receiver is the CRT. To prevent X-ray radiation, you

should use the same type of CRT when replacing it.

4. Some components used in this receiver have safety-related characteristics preventing the CRT

from emitting X-ray radiation. For continued safety, replacement component should only be made

after referring the Product Safety notice below.

SAFETY PRECAUTION

1. The high voltage in the TV reaches to 22KV when the TV is in operation. Be more careful during

opening the back cover.

a) The high voltage existing in the TV is very dangerous. Refer servicing to qualified personnel

only.

b) Before removing the high voltage cap. Discharge the anode of the CRT and the chassis in

case of electric shock.

c) Wear a pair of goggles when handling the CRT to avoid broken pieces damaging your eyes.

d) Do not hold the CRT neck in case of causing damage to the CRT.

2. When the power cord needs replacing, use the same one as that provided by AKIRA factory.

3. Voltage exists between the hot and cold ground when TV is in operation. Install a separation

transformer during repairing or connecting to any tester for the sake of safety. The power of the

separation transformer should be beyond rated overall power.

4. When replacing a burnout fuse, use the one with the same specifications as the original.

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Model No: 21SHS3-CE.doc

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5. When replacing old wire, wind new one round the shaft to weld. When replacing components with

safety in performance, use the same type as that specified by AKIRA and install it in the former

way.

6. Never place wire near high-temperature or high-voltage components.

7. An isolation transformer should be connected in the power line between the receiver and the AC

line when a service is performed on the primary of the converter transformer of the set.

8. Comply with all caution and safety-related notes provided on the cabinet back, inside the cabinet,

on the chassis or the picture tube.

9. When replacing a chassis in the cabinet, always be certain that all the protective devices are

installed properly, such as, control knobs, adjustment covers or shields, barriers, isolation resistor-

capacitor networks etc.. Before returning any television to the customer, the service technician

must be sure that it is completely safe to operate without danger of electrical shock.

PRODUCT SAFETY NOTICE

Product safety should be considered when a component replacement is made in any area of a receiver.

Components indicated by mark in the parts list and the schematic diagram designate components in

which safety can be of special significance. It is particularly recommended that only parts designated

on the parts list in this manual be used for component replacement designated by mark. No deviations

from resistance wattage or voltage ratings may be made for replacement items designated by mark.

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GENERAL DESCRIPTION

THE SURVEY

Table 1, the main IC and functions

Number Function IC Remark

1 Power supply KA5Q0765RT N611

2 CPU + SIGNAL PROCESSER OM 8370 /TDA9370 N301

3 Field driver STV9302A N401

4 Sound driver AN7522N N161

5 AV SWITCH TC4052BP

N801 (Video)

N161 (sound)

6 Memory AT24C08 N702

7 Photo-coupler PC817B N504

8 IR-receiver HS0038A2 U701

9 8V regulator L7808CV N503

10 5V regulator L7805CV N505

SIGNAL PROCESS

The TV signal enters into tuner (A201) from cable or antenna. Pin 10 and pin 11 of N301 are combined

to select the band. Pin 4 of N301 outputs PWM tuning signal. The 38.9MHz IF signal is coupled to

V308 (pre-amplify) and then to SAWF (Z301). After processed in the SAWF, the 38.9MHz signal gets

to pin 23 and pin 24 of OM8370. The IF circuit in OM8370 includes such unit as the AGC amplifying

circuit, 38.9MHz oscillator, PLL video demodulator, video amplifier, IF identify circuit and AFT

circuit. The demodulated signal (CVBS) comes from the pin 38 of OM8370, the sound signal comes

from the pin 44.

The internal CVBS signal needs norm identification then outputs from pin 38 of OM8370, via the trap

circuit (composed of the V351, Z351, Z354, V352 and so on) feeds back to the pin 40 of OM8370. The

RGB signal comes from pin51, Pin52, Pin53 of OM8370, and outputs to the CRT board. The internal

sound signal comes from pin 44 of OM8370 and then input to pin 1 and pin 12 of HEF4052BP. The

sound signals from RF and AV are selected in it. The selected signal is output from Pin 3 and pin13,

then input AN7522N (sound amplifier) or output from AV terminals.

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TECHNICAL SPECIFICATION

Test Item Conditional TD171

AC Operating

Range

RF&AV signal input with sound loud speaker

(volume maximum) & Picture set in Dynamic

mode

140Vac ~ 240Vac

Philips or Mono-scope pattern signal with howling

sound Contrast & Brightness set in Maximum,

sound increase maximum

90Watts

Total Power

Consumption

Standby Mode 14 Watts

Brightness & contrast set in Maximum Min: 26.2KVdc

Typical Design value Average: 26.5KVdc

EHT

Brightness &contrast Minimum Max: 27.8KVdc

Anode Current Brightness &contrast Maximum I

ABL

≤ 1.2mA

Heater Voltage TV operate normally V

Heater

= 6.2Vac

B

+

Normal operating VB

+

= 112Vdc

Sound power

output

RF signal input broadcasting at

217.25MHz/BG/DK(1KHz)

Volume is maximum

V = 6.3Vrms

P = 5Watts X 2

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GENERAL SPECIFICATION

14” 70W MAX

Power consumption

21” 90W MAX

Receive system DK/BG/I

Color system PAL/ SECAM/ NTSC

Vision intermediate frequency 38.9MHz

5.5 MHz(B/G)

Inter-carrier frequency

6.5MHz(D/K)

Chroma if frequency PAL 34.47/ 35.32MHz

Antenna type DIN TYPE 75 Ohm

VHF Low channel (VL) =48.25

to

147.25

MHz

VHF high channel (VH) =154.25

to

463.25

MHz

Channel receiving

UHF channel (U) =471.25

to

863.25

MHz

Tuning system VS tuning

AV IN/ OUT 2 AV STEREO IN + 1 AV STEREO OUT

Component IN 1 YUV-Component IN

VIDEO IN ----1.0 0.2V

p-p

75 Ohm

AUDIO IN ----0-2V (RMS)

VIDEO OUT ----1.0 0.2V

p-p

75 Ohm

AV IN/ OUT specification

AUDIO OUT ---- 0-2V (RMS)

OSD language

English, Russian, Turkish, French, Spanish,

Vietnamese, Indonesian, Arabian, Persian

Audio output power > 8W (1KHz, 0.5V INPUT, 10% THD

Safety authentication standard CB

LED indicator Power ON

Hand set type HS08

Hans set power supply Pin AAx2

Color picture tube 14” 21” 90 degree tube

Remote control distance 5m

Video/Audio (L/R) 2set input

YUV input

S-Video input

External input/output

Video/ Audio (L/R) 1 set output

 I

2

C Bus Control

 Auto Search

 Off/On Timer

 Teletext

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HORIZONTAL AND VERTICAL CIRCUIT

Through Synchronous separating circuit, the video signal is divided into horizontal-Synchronizing

signal and Vertical-Synchronizing signal. The horizontal-Sync pulse coming from pin 33 is transferred

to the horizontal-drive transistor.

The cathode driving voltage 180V vertical drive voltage +15V and –15V are all generated from

FBT.

The vertical sawtooth waveform is generated on the pin 21 and 22, and then enters the vertical

amplifier STV9302A. STV9302A is a 7 pins vertical deflection circuit (2 Amperes) for DC-coupled

90° or 110° deflection systems with frame frequencies from 50 up to 120 Hz. one supply voltage for

the scanning and second voltage supply for the flyback are needed.

The vertical drive currents of OM8370 pins 21 and 22 are connected to input pins 1 and 7 of

STV9302A. The vertical scanning output is coming from pin 5 and feed back to pin 1 by R405. The

supply voltage is ±15V at pin 2 and pin 4. C406 is the pump capacitor.

POWER SUPPLY

The IC of KA5Q0765RT is adapted in this chassis; it is the product of Fairchild. It supplies four DC

voltages, one is the +B＝110V, another is Hcc＝26V, the third is 13V (the sound drive voltage), the

fourth is +16V. The +16V can generate the +8V, +5V and +3.3V by the special generators.

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CHASSIS BLOCK DIAGRAM

HEAT

FOCUS

EHT

SCREEN

CRT

+300V

AUDIO AMPLIFIER

(N101) AN7522N

SP161

8Ω5W

SP162

8Ω5W

POWER SUPPLY

CIRCUIT

V1512

、、

V553 V1511

、

T

501

、

N504

Resistance

disturbance

C501

、 L502

AC150-260V

50/60Hz

Bridge

rectification

VD503-VD506

Filter C507

FBT(T402)

BSC25

110V

200V

24V

13V

16V

AV SWITH

N161

（）

CD4052

AV SWITH

N801

（）

CD4052

Video-out

Audio-out

（）

L

Audio-out

（）

R

Video-in1

Audio-in1

（）

L

Audio-in1

（）

R

Y

Cr

Cb

S-video

V-in2 A-in2

（）

LA-in2

（

R

）

15

14

13

9

10

1

2 3 4 5

11

15

14

13

12

9

10

12

10

4

2

6

8

9

PHILIPS UOC

TDA9351/61/81

VIDEO

AMPLIFIER

V912

，

V913

V922

，

V923

V932

，

V933

FIELD OUTPUT

POWER AMP

。

N401

（）

LA78040

HORIZONTAL

OUTPUT

V451

HORIZONTAL

DRIVE

V450

T450

HF TUNER

A101

IF PRE-AMP

V308

SAWF

Z301

KEY BOARD

REMOTE

RECEIVER

U701

MEMORY

N702

（）

ST24C08

11

42

62

63

44

47

48

46

43

38 7

TV AUDIO OUT

SIF TRAPS

Z351,Z352,Z354

V351

V352

40

10

11

BAND2

BAND1

23

24

6

64

2

3

6

5

SCL

SDA

53

52

51

21

22

33

+15V

-15V

15V

R

L

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FAULT FINDING TREES

A Three-None(no raster, no picture, no sound)

This failure is mainly caused by big-power circuit such as power supply, horizontal scanning, vertical scanning.

The detail checking and repairing steps are as follow.

0V

4.5-5.5V

YES

0V

＞

1V

0.6V

300V

N

O

YES

0V

300V

0V

115V

N

o variation

N

ormal

115V

0V

Others

24V

2V

8V

115V

LOW

N

O

variation

＜

50V

Test the voltage of C528B

Cut off R458

T

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1

8

V

,

2

4

V

,

a

n

d

1

2

V

VD525,VD1561,VR501,V542,

VD1517,V504,V1511

Check VD522,C528B

Recover R458, unplug

XS403 for a While,then

test the voltage of C528B

Check V451,T451,T450,

Deflection coil

Check L452,VD436,C461

Deflection coil

Voltage of C507

Check if V1513 collect-emitter

Was broken down

Check XR502,F501,power

Swich, AC cord and plug

Check the voltage

of V1513 collector

Check V1513,V1512,F501,XR502,VD503

Check T501

Test voltage of V1513 base

Check T501,VD1517,

C1515,C1517,V451,

VD522-VD529

C455,C456,T451

C467

Check if it get right

When cut off V504

Test the voltage of

N

301 pin1

CPU has sent the

Power-off signal

Check if V504

is broken down

Check V1513

Check R539,V1553,VD1561

N

504,V1511,V1512,R556

N

301 pin39voltage

N

301 pin33 voltage

Check N301,N401

V450 pin C voltage

Check VD543,C525,

]R454,C453,T450,

C455,V451

Check R452,V450

Check T451

Check V451 pin C voltage

Check T451,V451,R458

＞

130V

Others

115V

0V

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B Two-None (no picture, no sound)

The failure shows that the set does not display the picture but it has noise wave or blue background or OSD on the screen. This means that the circuits of power supply, horizontal scanning, vertical scanning

and video amplification are normal and they are not considered in the repairing. The failures are mainly in the small signal processing circuits.

Before checking these circuits, a kind of practical test method is introduced. It is called “Signal-input way ”. The detail is described as follow: We can use the resistance function of an analog multimeter,

connect the red pole (negative in ohm scope) on the circuit board ground, then touch softly the test point with another pole (black pole) in ohm scope meanwhile observe the reactivity on the output device.

Note : In the TV test, we mainly observe the noise wave on the CRT and listen to the noise voice liking as “Ka…..Ka” from the loudspeakers.

1. No picture

YES

N

o variatio

n

Out of the “ 0-33V ” range

0V

N

O

No picture

Check the “ +5V ” voltage on A101

Check RF signal input and adaptor

Check N703, A101

Check R301,R302,

N

301,A101

Check the “ VT ” voltage when auto searching

Check R707, C707, A101

The voltage between VL and BH vary from 0V to

5V or not when auto searching

Check R703,N703,C703A

The voltage on the C703

Check the voltage on the C705

Check ,V701,N301, R701, R701A

,R704,R705,C701,C705,C706

Check if A101 has input signal

0V

YES

In the “ 0-33V ” range

5V

＜

33V

＝

33V

0-33V

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YES

0V

＞

3.8V

＜

2V

Exam the voltage of “ AGC ” on A101 without antenna

Check R317, R318, R316,C307,A101,N301

Test the voltage on pin 14, 54, 56of N301

N

O

YES

N

O

≥2V

YES

N

O

0V

YES

Check,L331, C333, L752,C753A, L751, C751

Test the voltage on pin 51, 52, 53, 50 of N301

Check N505, N301

Check N503, N301,C532, R565,C524,

,VD561,V542

Observe if there is snow-noise-wave disturbance on the CRT via using “Signal-input way ” by touching pin 23 and pin 24 of N301

Observe if there is snow-noise-wave disturbance on the CRT via using “Signal-input way ”by touching pin 17 of N301

Check R331,C336,C337

Observe if snow-noise-wave disturbance on the CRT via using “ signal-input way ”by touching pin 40 of N301

Test if there is the sync signal on the pin 39 of N301

Check V351,V352,L351,Z351,C364

Check C323,A101,N301

Observe if there is snow-noise-wave disturbance on the CRT via using “ Signal-input way ” by touching pin 38 of N301

Check if voltage on pin 31 of N301 is 1.7V

Check C361,C362,L361,N301

Observe if these is snow-noise-wave disturbance on the CRT via using “ Signal-input way ” by touching pin 51,52,53 of N301

Check R381,R382,R383,V912,V922,V932,N301

8V

5V

N

O

N

O

N

O

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5. No sound

In this kind of failure, first of all we should observe if there is the picture on the CRT. It proves the small signal circuit to work correctly with the picture on the CRT and we only check the sound signal

processing and sound amplification circuit. The repairing method(B1) may be referred without picture. The detail checking and repairing steps are as follow.

Note:

Before repairing, assure that the volume is on and the state of set is in “TV” .

＜

5V

YES

N

O

N

O

＜

8V

YES

N

O

YES

N

O

Hear if there is the voice liking “Ka…Ka ” in the loudspeaker via using “ Signal-input way ” by touching pin 7 of N301

Check C367,R369,V395,N301

Hear if there is the voice liking “Ka…Ka ” in the loudspeaker via using “ Signal-input way ” by touching pin 3 of N121

Hear if there is the voice liking “Ka…Ka ” in the loudspeaker via using “ Signal-input way ” by touching pin 44 of N301

Check R733, C732, N301

Check R126,N505, N121

The voltage on pin 9,10of N121

Check 8V-power supply

Hear if there is the voice liking “Ka…Ka ” in the loudspeaker via using “ Signal-input way ” by touching pin 2,10 of N701

Check VD521,R165,C522,T501,N161

The voltage on pin 16 of N121

Hear if there is the voice liking “Ka…Ka ” in the loudspeaker via using “ Signal-input way ” by touching pin 13 of N121

Check R157,C157,N161

Hear if there is the voice liking “Ka…Ka ” in the loudspeaker via using “ Signal-input way ” by touching pin 6,8of N161

The voltage on pin 1 of N701

Check R153,C153,R154,C154,N121

Check C157,C153, N101

Check SP161, SP162, N161

N

O

8V

12.5V

N

O

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C Only horizontal line in the middle of the screen:

If vertical deflection circuit does not work, this kind of failure will happen. In deflection yoke, there only has horizontal sweeping , the electron beam in the CRT only moves in the horizontal orientation , so

form this failure.

(While checking horizontal and vertical deflection circuit’ s failure , we have better to use an oscilloscope.)

Abnormal

N

ormal

N

ormal

Abnormal

24V

0V

Abnormal

N

ormal

The waveform on the pin 21,22 of N301

Measuring the waveform on the deflection yoke

Check C401,C402,R401,R402,N301

The voltage on pin 2 of N401

Check VD470, R470,VD401,N401

Check N402

Measuring the waveform on pin 1 of N401

Check R405, C408, N401, N301

Measuring the waveform on pin 5 of N401

Check R407,C408,R406,XS403, deflection yoke

Abnormal

The deflection yoke on the CRT

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D Only vertical line in the middle of the screen

This is a dangerous failure. It probable causes flashover and smoking inside the set. Don’ t let your TV work for a long time as this failure appears. Because the electron beam can not move in the horizontal

orientation, the failure should be in the horizontal deflection circuit. We mainly check the open-circuit fault in horizontal deflection circuit. The detail checking and repairing steps are as follow:

E UOC does not work

In television, remote-control system is similar with the computer system. In theory , it can work if it holds two conditions as follow:

1) The power supply: In general, it is 5V, the error is not above 10% and the disturbance pulse is as small as possible.

2) The clock pulse: In TDA93XX circuit, the clock pulse is generated by pin58 / pin59 of N301 and 12M crystal oscillator.

Television’ s remote-control system also needs reset circuit that can preset the values in internal register. The circuit around pin57

of N204 is called auto-reset circuit. If UOC detects errors in resetting, it will come to the state of programme protected.

YES

N

O

Vertical line

Repair CRT

The horizontal yoke is opened or not

Whether “ XS403” is opened

Check if there is bad solder between XS403, and the main board

Check L452, VD436, C467,C455,especial in inductive components and connector

N

O

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The detail checking and repairing steps are as follow:

F No OSD (On Screen Display)

This failure is usually cause by the circuit of character generated and located. Most of reasons are that the horizontal and vertical flyback pulse signals do not come to UOC.

We can judge this failure by measuring the wave of the character in an oscilloscope.

The detail checking and repairing steps are as follow:

3V

＜

3.3V

=14V

＜

3.3V

YES

=3.3V

N

O

＜

3.3V 3.3V

N

301 does not work

The voltage on the pin 56 of N301

Observe if there is sine wave on the pin 58 or pin 59

of N301 with an oscilloscope

Check the voltage on the positive pole of C548

N

O

YES

3.3V

Check alternant voltage on secondary coil of N505,

Check X761, N301

Check R561,VD564

Check the voltage on the pin 54 of N301

Check T501, VD522,R565

Check N301

Check the voltage on the emitter of VD564

Check the voltage on the positive pole of VD522

Check VD522, T501

Check R565,R546,N505

Check L752,L753

YES

N

O

Check FBT T451

No OSD

Check the wave on the pin 7 of FBT

Check C482, R485, VD483, R487, N301

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IC BLOCK DIAGRAM

Fig 1: OM8370 Illustration

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MAIN CHIP INSTRUCTION

Pin 1 Standby control, “1” is on, “0” is off.

Pin 2 SCL

Pin 3 SDA

Pin 4 Tuning PWM output

Pin 5 Auto AV control SW, connected with the SCART 8

th

pin. Input. The rising edge or

the falling edge operates.

Pin 6 Key board input.

Pin 7 Volume

Pin 8 Mute control, “1” is mute, “0” is off.

Pin 9, Pin 12,

Pin 18, Pin 30,

Pin 35, Pin 41,

Pin 55

GND

Pin 10 BAND 1 control output.

Pin 11 BAND 2

Pin 13 SECAM PLL, connected with a capacitance (no use in this type).

Pin 14 +8V power source supply

Pin 15 Using a capacitor of 220n in series to GND. This pin decouples the internal digital

supply voltage of the video process and minimizes the disturbance to the sensitive

analogue parts.

Pin 17 Phase-1 control loop filter connected to pin 17 is suitable for various signal

conditions like strong /weak and VCR signal. This is achieved by switching of the

loop filter time constant by changing the Phase-1 output current.

Pin 18 GND

Pin 19 Bandgap decoupling, the bandgap circuit provides a very stable and temperature

independent reference voltage. This reference voltage (4.0V) ensures optimal

performance of the analogue video processor part of the OM8370 and is used in

almost all functional circuit blocks.

Pin 20 East-west pillow signal output.

Pin 21, Pin 22 Vertical drive output.

Pin 23, Pin 24 IF input.

Pin 25 Reference current/ This pin requires a resistor to ground. The optimal reference

current is 100mA which is determined by this resistor. The 100mA reference

current should not be changed because the geometry processor is optimized for this

current. Furthermore the output current of vertical drive and EW are proportional to

this current.

Pin 26 Vertical sawtooth. This pin requires a capacitor to ground of 100nF.

Pin 27 AGC output. This output is used to control (reduce) the tuner gain for strong RF

signals.

Pin 28 Audio de-emphasis.

Pin 29 Sound decoupling. This pin requires a capacitor connected to ground. The pin acts

as a low pass filter needed for the DC feedback loop.

Pin 30 GND

Pin 31 Sound loop filter.

Pin 32 AVL filter

Pin 33 Horizontal drive signal output, needs a resistor in series to +8V.

Pin 34 Sandcastle output /flyback input.

Pin 35 External audio input, this pin should be grounded in this chassis.

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Pin 36 EHT tracking /over voltage protection. If something is wrong, the anode high

voltage rise the heater voltage will rise too. When the rising voltage arrive some

limit, the V406 works, the voltage of pin 36 will exceed 3.9V. The OM8370 will

stop working.

Pin 37 PLL loop filter.

Pin 38 CVBS output. Monitor or RF videos can be selected.

Pin 39 +8V supply source

Pin 40 CVBS input

Pin 42 Y signal input

Pin 43 C signal input

Pin 44 Main audio output. This pin is connected to the TDA9859.

Pin 45 RGB signal input blanking.

Pin 46, Pin 47,

Pin 48

RGB signal input.

Pin 49 ABL. It means been current limiter input. R410 is the control resistor.

Pin 50 Black current input from the CRT board.

Pin 51, Pin 52,

Pin 53

RGB drive signal output to the CRT board.

Pin 54 +3.3V

Pin 55 GND

Pin 56 +3.3V

Pin 57, Pin 58,

Pin 59

12MHz crystal

Pin 60 Reset. NC in this chassis

Pin 61 +3.3V

Pin 62 NC

Pin 63 This pin is connected to the HEF4094. Functions expending.

Pin 64 IR signal input.

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akira 21SHS3/CE User manual

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